Emitting assembly of an electronic bombardment gun

ABSTRACT

An electronic bombardment gun comprising the emitting assembly of a goffered washer, an insulating spacer, a central electrode, a conical perforated filament, said filament being provided with a flange at its widest portion and with an emitting annular end portion pierced with an orifice at its narrowest part.

United States Patent [72] Inventor Jean-Pierre Peyrot 8 domaine duBel-Abord, Chilly-Mazarin, Essonne, France [21] Appl. No. 880,715 [22]Filed Nov. 28, 1969 [45] Patented Oct. 12, 1971 [32] Priority Nov. 29,1968 [3 3] France [31 1 176,086

[54] EMITTING ASSEMBLY OF AN ELECTRONIC BOMBARDMENT GUN 13 Claims, 12Drawing Figs.

[52] U.S.Cl 313/341, 3 1 3/23 8 [51] Int.Cl H01j 1/15 [50] Field ofSearch 313/237, 238, 341

[56] References Cited UNITED STATES PATENTS 1,980,447 11/1934 Stine313/238 X Primary ExaminerDavid Schonberg Assistant Examiner-Paul A.Sacher Att0rneyKarl W, Flocks ABSTRACT: An electronic bombardment guncomprising the emitting assembly of a goffered washer, an insulatingspacer, a central electrode, a conical perforated filament, saidfilament being provided with a flange at its widest portion and with anemitting annular end portion pierced with an orifice at its narrowestpart.

EMITTING ASSEMBLY OF AN ELECTRONIC BOMBARDMENT GUN The present inventionrelates to an electronic welding gun and, more particularly, to abombardment gun of the directheating type with an annular throttledcathode.

The invention has for its main object a filament which combines theadvantages of direct heating guns and indirect heating guns.

It has also for its objects other arrangements which will be describedmore explicitly during the course of the description which follows,especially the following:

The filament is of the type having coaxial conductors, which provideseasy handling and accurate adjustment in position together with rapidassembly and dismantling;

It is applicable to direct-heating guns of the PIERCE type, which arethe simplest, the least bulky and the least expensive guns.

These guns, in which the heated filament serves as an emitting cathode,have a considerably defect; their filaments are fragile because they aremade either from a very thin stamped sheet of metal or of very finewire.

On the other hand, the setting in a good position -of the emittingportion is very difficult to carry out with respect to the cathodeelectrode, because of this fragility.

Another important defect which can be attributed to the deformation ofthis filament during heating and cooling which influences the accuracyof the emission image and the long life of the said filament.

On the other hand, indirect-heating guns, although of much morecomplicated construction, offer certain advantages:

No influence of the deformation of the heating filament;

Considerably rigidity of the emitting cathode;

Accurate emission image;

Possibility of a smaller emission face;

Very accurate positioning of the emissionface with respect to thecathode electrode.

By creating a rigid coaxial filament, the invention retains theadvantages of direct heating, namely:

Simplicity of construction;

Small overall size;

Moderate production cost, with which are combined the advantages ofindirect heating, namely:

No deformation of the filament;

Great rigidity of the emitting portion;

Accurate emission image;

Possibility of a very small emitting face;

Very accurate maintenance in a good position of the emitting surfacewith respect to the cathode electrode.

In addition, it offers other very valuable advantages which are notpossessed by either of the types of gun referred to, namely:

rapid, easy and accurate positioning of the filament;

very great simplification of the filament supports through which thecurrent supply is effected;

stability during heating due to the symmetrical arrangement,

reliability in construction, by virtue of the permissible tolerances,

guaranteed interchangeability,

very easy utilization of electronic bombardment in a protected cell, dueto the fact that by virtue of its qualities, this filament can bereadily changed at a distance by remote control, for example,

moderate production cost of the filament,

further substantial reduction in production cost with respect to thecheapest direct-heating guns.

The invention is particularly directed to certain methods of applicationespecially of electronic bombardment guns intended for welding, and alsoto certain methods of construction, and it is still more particularlydirected, by way of new industrial products, to direct-heatingelectronic bombardment guns comprising the application of the samearrangements, their special elements, together with the electronicbombardment guns which comprise similar elements.

Other characteristic features and advantages will be brought out fromthe description which follows below, reference being made to theaccompanying drawings which show, purely by way of indication and not inany limitative sense, two forms of embodiment of the invention.

In these drawings:

FIG. 1 is a view of a conventional filament of metal foil cutout andfolded to shape;

FIG. 2 is a view of a conventional filament of metal foil, cutout,shaped and punched;

FIG. 3 is a view of a conventional filament of coiled wire;

FIG. 4 is a view of a conventional filament of wire wound in a spiral;

FIG. 5 is a diagram of the mounting of a foil filament in a conventionaldirect-heating gun;

FIG. 6 is a diagram of the mounting of a wire filament in a conventionaldirect-heating gun;

FIG. 7 is a basic diagram of the mounting of a conventionalindirect-heating filament and its emitting cathode;

FIG. 8 is a perspective view of a coaxial filament according to theinvention;

FIG. 9 is an exploded view of the coaxial filament shown in FIG. 8;

FIG. 10 is a half-sectional view of the coaxial filament of FIG. 8;

FIG. 11 is a view in cross section of the mounting of a coaxial filamentof FIG. 10, in a gun of the PIERCE type;

FIG. 12 is a view in cross section of an alternative form.

There is shown in FIG. 8 a metallic filament body 10 of tantalum,tungsten, tungsten/rhenium or other metal, of conical form andcomprising at its lower portion an annular surface 11, having athickness of 0.05 mm. for example and of slightly domed shape, piercedat its center with a hole of 0.4 mm. in diameter. This circular surface11 is inscribed in a cylinder I2 having a height f=l.5 mm. and athickness c=0.3 mm. This cylinder is continued at its upper portion by acone 13 having a height h=6.5 mm. a thickness c=0.3 mm. and a largediameter d=4.8 mm. This cone is pierced on its periphery with a numberof openings 14 permitting evacuation of air so as to obtain the vacuumnecessary for the bombardment. This cone terminates at its upper portionin a flange 15 having an external diameter d=8 mmxand a thickness e=0.3mm.

A central metal electrode 16, for example of tantalum, tungsten,tungsten/rhenium or other metal has the shape of a cylinder 17 having adiameter 8=l mm. and a height of h'=7 mm., terminating at its lowerportion in a smaller cylinder 18 giving a diameter D -0.4 mm. and aheight A=2 mm.

An insulating spacing disc 19, of alumina for example, of cylindricalshape, having an external diameter d=8 mm. and a thickness e=l mm., acomprises at its lower portion a conical boss 20 which during assemblyis centered in the upper portion of the cone 13. In the central part ofthis boss is pierced a hole 21 having a diameter D. The upper portion ofthe spacer is formed into a conical dished portion 22.

A metal washer 23 of tantalum, tungsten, tungsten/rhenium or othermetal, having an external diameter d=8 mm. and a thickness e=0f3 mm. isprovided at its center with a stamped dished portion 24 which iscentered during the assembly in the dished portion 22 of the spacer 19.This dished portion gives a high degree of elasticity to the washer 23,which behaves like a flexible diaphragm and thus enables all thermalfatigue due to differences of expansion to be avoided. In other words,the punched out form of the washer 23 permits the expansion of thecentral electrode 16 without adverse effect.

In the hole 40 of diameter 0.4 in the circular surface 11 of thefilament 10, the cylinder 18 of the central electrode 16 mounted with aclose fit.

A weld is effected by electronic bombardment at 27 and in the directionof the arrow f2, in order to bind together intimately the parts 10 and16.

The spacer 19 is placed on the flange 15 and its conical bearing surface39 is centered in the cone I3 of the filament body 10.

The goffered metal washer 23 is placed on the spacer 19 and is centeredin the dished portion 22 of this spacer. On other hand during thisoperation, the cylinder 17 of the central electrode 16 is centered witha close fit in the hole 26 of the washer 23.

A weld by electron bombardment will effected at 29 in the direction offl so as to bind together the washer 23 and the central electrode 16 inan intimate manner.

The compact assembly thus formed is a coaxial filament for adirect-heating gun, for which it enables its own advantages alreadyrecited to be combined with those of conventional indirect-heating guns.

The basic diagram of FIG. 11 illustrates very clearly the simplicity ofthe inputs of high-voltage current pole pieces 31 and 32, together withthe simplicity of mounting or removal of the filament 10. The metallicparts 31 and 32, insulated from each other by an insulating member 33,constitute the inputs of the high-voltage current. In the part 31 hasbeen bored a hole 34 to permit the passage of the filament. in the parts31 and 33 has been machined a spotface or blind orifice 35, in which thefilament comes to rest and is centered. in the part 32 is provided athreaded hole 36 in which is screwed a metal nut 37. By tightening thisnut, the parts l0, l9 and 23 are compressed against each other.

The pressure and the contact of the nut 37 against the part 23 and inthe threaded portion 36 of the part 32, permits an excellenttransmission of the high-voltage current from the part 32 to the parts23 and 16.

The pressure of the nut on 31 and 10, and the contact of these partswith each other, permits the transmission of the highvoltage currentbetween the parts 31 and 10.

The passage of the current coming from the parts 23 and 16 into thecoaxial annular emitting ring 11 of the part 10, while passing throughthe circular surface having a section very much less than that of theparts 10, 16 and 23, causes it to heat-up. This part of the filament isbrought up to high temperature and becomes emitting under the commonconventional conditions of welding by electron bombardment. Inparticular, there can be sewn in FIG. 12 an alternative form in which,for reasons of bulk, in the case of welding in places difficult ofaccess, the filament is flatter and the current supply inputs are madein different ways and are embedded in the insulated trolley 30 mountedon rollers 28. The parts to be welded, 9 and 9, are placed in theimmediate vicinity of ring 11.

There has thus been constructed according to the invention, a compactcylindrical assembly having the smallest possible dimensions.

It will of course be understood that the present invention has beendescribed above purely by way of indication and not in any [imitativesense and that any modification of detail may be made thereto, inconformity with its spirit, without thereby departing from its scope.

What I claim is:

l. The emitting assembly of an electronic bombardment gun comprising:

a conical perforated filament having a flange at its widest portion andan emitting annular end portion pierced with an orifice at its narrowestportion,

a central electrode centered in said filament,

an insulating spacer centered at the widest portion of said filament,

and a goffered washer centered in relation to said insulating spacer.

2. The emitting assembly as claimed in claim 1, in which said spacer isprovided with a dished portion of a first conical bearing surface whichis mated to the interior of said flange against the widest portion ofthe cone of the filament body.

3. The emitting assembly as claimed in claim 1, in which the gofferingof said washer comprises a conical seating which is applied against asecond conical bearing surface provided on a face of said spaceropposite to said first'conical bearing surface.

4. The emitting assembly as claimed in claim 1, in which said insulatingspacer is of refractory material and is pierced with a central orificethrough which the electrode slides freely.

5. The emitting assembly as claimed in claim 1, in which the electrodeis a forced fit into and is welded to one extremity of the bottom of thefilament and its other extremity is fitted and welded to the interior ofthe goffering of said washer.

6. The emitting assembly as claimed in claim 5, in which the electrodeis composed of a portion of large diameter and a portion of smalldiameter.

7. The emitting assembly as claimed in claim 1, comprising an electrodemade of tantalum.

8. The emitting assembly as claimed in claim 1, comprising a electrodemade of tungsten/rhenium.

9. The emitting assembly as claimed in claim 1, comprising a washer madeof tantalum.

10. The emitting assembly as claimed in claim 1, comprising a washermade of tungsten/rhenium.

11. The emitting assembly as claimed in claim 1, further comprising afirst pole-piece pierced with an internally threaded hole having adiameter greater than the external diameter of said washer; a secondpole-piece pierced with an orifice having a diameter greater than themeans diameter of said conical filament, an insulating member piercedwith an orifice corresponding to the common diameter of said washer andof said flange, a spotface provided in said insulating member and insaid second pole-piece permitting the clamping of the washer and thespacer against the flange by means of a nut screwed into said internalthreaded portion.

12. The emitting assembly as claimed in claim 11, in which thepole-pieces are connected to a source of high-frequency current.

13. The emitting assembly as claimed in claim 12, in which said polepieces are connected on an insulating trolley, said filament being givenan extra-flat form so as not to project from the external surface of thetrolley in the direction of parts to be welded.

1. The emitting assembly of an electronic bombardment gun comprising: aconical perforated filament having a flange at its widest portion and anemitting annular end portion pierced with an orifice at its narrowestportion, a central electrode centered in said filament, an insulatingspacer centered at the widest portion of said filament, and a gofferedwasher centered in relation to said insulating spacer.
 2. The emittingassembly as claimed in claim 1, in wHich said spacer is provided with adished portion of a first conical bearing surface which is mated to theinterior of said flange against the widest portion of the cone of thefilament body.
 3. The emitting assembly as claimed in claim 1, in whichthe goffering of said washer comprises a conical seating which isapplied against a second conical bearing surface provided on a face ofsaid spacer opposite to said first conical bearing surface.
 4. Theemitting assembly as claimed in claim 1, in which said insulating spaceris of refractory material and is pierced with a central orifice throughwhich the electrode slides freely.
 5. The emitting assembly as claimedin claim 1, in which the electrode is a forced fit into and is welded toone extremity of the bottom of the filament and its other extremity isfitted and welded to the interior of the goffering of said washer. 6.The emitting assembly as claimed in claim 5, in which the electrode iscomposed of a portion of large diameter and a portion of small diameter.7. The emitting assembly as claimed in claim 1, comprising an electrodemade of tantalum.
 8. The emitting assembly as claimed in claim 1,comprising a electrode made of tungsten/rhenium.
 9. The emittingassembly as claimed in claim 1, comprising a washer made of tantalum.10. The emitting assembly as claimed in claim 1, comprising a washermade of tungsten/rhenium.
 11. The emitting assembly as claimed in claim1, further comprising a first pole-piece pierced with an internallythreaded hole having a diameter greater than the external diameter ofsaid washer; a second pole-piece pierced with an orifice having adiameter greater than the means diameter of said conical filament, aninsulating member pierced with an orifice corresponding to the commondiameter of said washer and of said flange, a spotface provided in saidinsulating member and in said second pole-piece permitting the clampingof the washer and the spacer against the flange by means of a nutscrewed into said internal threaded portion.
 12. The emitting assemblyas claimed in claim 11, in which the pole-pieces are connected to asource of high-frequency current.
 13. The emitting assembly as claimedin claim 12, in which said pole pieces are connected on an insulatingtrolley, said filament being given an extra-flat form so as not toproject from the external surface of the trolley in the direction ofparts to be welded.